The present invention relates to an oil pan that may be used with an engine, e.g., an internal combustion engine. The oil pan includes a shell of plastic material, and a support structure, having a plurality of perforations, that is fixedly attached to the exterior surfaces and/or the interior surfaces of the plastic shell. The shell is formed by molding plastic material onto the support structure. During the molding process a portion of the plastic material of the shell extends through at least some of the perforations in the support structure, embedding the edges of the perforations therein, and thereby fixedly attaching the support structure to the shell.
In many instances it is desirable to reduce the weight of a mechanical apparatus for reasons including, for example, ease of transport and, in the case of the transportation industries, improved fuel efficiency. In the automotive industry one approach to reducing the overall weight of the vehicle has involved replacing various structural metal components, such as metal body panels, with lighter weight plastic components. More recently, attention in the automotive industry has turned towards replacing metal components of the engine, e.g., the oil pan, with molded plastic. A molded plastic oil pan must be resistant to a wide range of temperatures, e.g., from xe2x88x9240xc2x0 C. to 150xc2x0 C., and various fluids, such as engine oil, fuels, salt and water. In addition to providing reduced weight, a molded plastic engine component, such as a molded plastic oil pan, must also provide at least the same degree of mechanical strength and rigidity as the metal component that it is replacing. Unfortunately, molded plastic parts typically have lower strength and rigidity compared to equivalent parts fabricated from metal.
It would be desirable to develop a molded plastic oil pan, e.g., for use as a component in the engine of an automobile, that has reduced weight. It is also desirable that the molded plastic oil pan have, in addition to reduced weight, strength and rigidity that is at least equivalent to that of a metal oil pan.
U.S. Pat. No. 6,131,543 discloses an oil pan for an internal combustion engine that consists of an outer latticed girder structure of a light-weight high-strength material, e.g., of metal, and an inner thin-walled shell of plastic material. The latticed girder structure and the thin-walled shell of the ""543 patent are disclosed as forming an integral oil pan structure. The latticed girder structure is disclosed as being placed into a die, into which plastic material is then injected to form the plastic shell in the ""543 patent. In FIG. 2 of the ""543 patent, the plastic shell and the latticed girder structure are shown as being attached one to the other by means of portions of the latticed girder structure extending through apertures in the plastic shell.
International Patent Publication No. WO 01/83954 A1 discloses an oil pan module for internal combustion engines that is formed by injection molding of a thermoplastic material, e.g., thermoplastic polyamide reinforced with glass fibers. The oil pan of WO 01/83954 A1 is disclosed as being provided with outer and inner reinforcing ribs injection-molded onto it.
U.S. Pat. No. 4,898,261 discloses a plastic oil pan for an internal combustion engine, which includes a plurality of reinforcing walls integrally formed along the sidewalls. The reinforcing walls of the oil pan of the ""261 patent are disclosed as increasing the mechanical strength of the oil pan such that it can support the engine when the engine rests on the oil pan during installation or repair procedures.
In accordance with the present invention, there is provided an oil pan comprising:
(a) a shell (11) of plastic material, said shell having interior and exterior surfaces, the interior surfaces of said shell defining a hollow interior (40); and
(b) a support structure (14) in abutting relationship with and being fixedly attached to at least one of (i) at least a portion of the exterior surfaces of said shell and (ii) at least a portion of the interior surfaces of said shell, said support structure having a plurality of perforations (20) having edges,
wherein said shell is formed by molding of plastic material onto said support structure, a portion of the plastic material of said shell extends through at least some of said perforations of said support structure, the edges of said perforations being embedded in the plastic material extending therethrough, thereby attaching fixedly said support structure (b) to said shell (a).
The features that characterize the present invention are pointed out with particularity in the claims, which are annexed to and form a part of this disclosure. These and other features of the invention, its operating advantages and the specific objects obtained by its use will be more fully understood from the following detailed description and accompanying drawings in which preferred embodiments of the invention are illustrated and described.
Unless otherwise indicated, all numbers or expressions, such as those expressing structural dimensions, quantities of ingredients, etc. used in the specification and claims are understood as modified in all instances by the term xe2x80x9cabout.xe2x80x9d